Machine tool



July 14, 1953 w. L.. BENNINGHOFF l-:rAL R 23,684'

MACHINE TOOL 13 Shoots-Sheet 1 Original Filed Fab. 26, 1945 NNhN ATroRNEY w. l.. BENNINGHOFF Erm. Re. 23,684

July 14, 1953 MACHINE TUOL ortgingl Filed Fab. 26. 1945 ATTORN EY INVENTORS July 14, 1953 w. l.. BENNINGHQFF ETAL Re- 23,684

MACHINE TOOL 13 Shoots-Sheet 3 Original Eilld FIb. 26, 19454 INVENTORS.

ATTORNEY July 14, 1953 v w. L. BENNINGHQFF erm. Re. l23,684

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INVENTORS BY I a 1 ATTORNEY Ressuecl July 14,. 1953 MACHINE TOOL William L. Benninghon, Waite Hill Village, and Alexander F. Robertson, South Euclid, Ohio, lassignors to The Pipe Machinery Company,

Cleveland, Ohio, a corporation of Ohio Original No. 2,576,095, dated November 27, 1951I Serial No. 579,752, February 26, 1945.

Application for reissue January 16, 1952, Serial No.

25 Claims.

l The invention relates to machine tools and particularly to tools for cutting screw threads, including taper threads. The invention is applicable to the cutting of both exterior and interior threads, but for purposes of explanation it will be shown as embodied in apparatus designed for the cutting of external threads.

It is a principal object of the invention to provide a machine for cutting screw threads that is largely automatic in operation and capable of performing rapid, yet uniform and reliable, operations upon work pieces fed to it in succession, with resultant large capacity for the turning out of work of high quality.

The invention has for another of its objects the provision in a thread-cutting machine of the t'pe having thread-forming apparatus with collapsible chasers, a work chuck, means for eecting relative rotation of the said apparatus and chuck and means for effecting their relative axial movement, first toward and then away from each other, of means operating automatically in succession to close the chuck upon a work piece presented to the chasers, effect [to] a slow forward feed of the work piece in relation to the chasers,

a rapid retraction of the work piece from the chasers and opening of the chuck to release the workpiece.

A further object of the invention is to provide a machine for attaining the above stated objects having control and actuating devices energized by fluid pressure with resultant attainment of high speed movements for various parts of the mechanism preparatory to and following the actual thread-cutting operation, with resultant attainment of a short over-all time of the operating cycle.

Another object of the inventionis to provide thread-cutting apparatus of the receding-chaser type in which the'chasers are movably mounted in one end of aA hollow rotary spindle and are actuated by means supported from interior surfaces of the spindle while the spindle'itself is rotatably supported by exterior bearings one of which is close to the chasers for firm support thereof.

The invention has for another object the provision of thread-cutting apparatus of the receding and collapsing chaser type in which the chasers are mounted on a rotary spindle and have their actuating mechanism constructed and arranged within the spindle so that it is possible both to secure great compactness and dust-proof enclosure for the mechanism and at the same time to provide adequate bearing support for Matter enclosed in heavy brackets I: appears in the original patent but forms no part et this reissue specification; matter printed in italics indicates the aadditions made by reissue.

the spindle relatively close to the chasers so as to attain firmness of support for the chasers and the advantages resulting from such support.

Another object of the invention is to provide a rotary 4spindle thread-cutting apparatus of the character above indicated having improved means by which the apparatus can conveniently be adjusted to cut threads of various tapers.

A further object of the invention is to provide thread-cutting apparatus of the receding chasertype having improved means for varying the diameters of the thread cut.

The invention has for another of its objects the provision, in a`metal-working machine comprising a-cutter mechanism, a work-holding mechanism and a feed carriage for supporting one of said mechanisms, of means for moving the carriage comprising a drive cam. variable speed gearing for moving the cam to effect carriage feed movement during the cutting operation of the machine, and fluid pressure operated means for moving the cam in the reverse direction independently of said gearing to eilect a rapid return movement of the carriage.

Another object of the invention is to provide a machine of the character referred toA in the I last stated object in which the cutter mechanism is adapted to form screw threads and in which the feed cam is adjustable to compensate for errors of lead that might otherwise occur in the thread cut by the machine.

Another object of the invention is to provide a machine such as referred to in the last but one of the foregoing objects in which the cutter mechanism is adapted to form screw threads and in which the connection between the feed carriage and its actuating cam is adjustable to provide for cutting threads of different lengths while permitting support for the work relatively close tothe cutters.

The invention has for another of its objects the provision in a metal-working machine comprising a thread-cutting mechanism, a workholding mechanism and a feed carriage for supporting one of said mechanisms, of feed mechanism for the carriage comprising a drive cam, and readily disengageable connecting means between the cam devices and the carriage to permit the latter to be moved back away from the thread-cutting mechanism and afford access thereto.

A further object of the invention is the provision, in a. thread-cutting machine in which work to be threaded is held by a fluid actuated chuck supported by 'a feed carriage and the operation of the carriage and chuck are automatically controlled, of improved means for timing the action of the chuck in relation to the movement of the carriage.

The invention has for still another object the provision, in a thread-cutting apparatus of the type in which the cutters slowly recede during their' cuttingv operation, rapidly collapse at the end of their cutting operation and are automatically re-set for the start of a succeeding cutting operation. of improved means for manually disconnecting the automatic re-setting means, effecting collapse of the cutters, re-setting the cutters and restoring the operation of the automatic re-setting means.

The invention has various other objects, more or less incidental or ancillary to those above noted, which will appear in the following description of an exemplary embodiment of our improvements shown in the accompanying drawings.

With all of the various objects in view the invention consists in features of construction and combination of parts to be explained in the following detailed description having reference to )the accompanying drawings and will be particularly pointed out in the appended claims.

vIn the drawings,

Fig. l is a front elevation of a machine embodying the invention, it being designed to cut external taper threads on pipes, rods and the like.

Fig. 2 is an enlarged elevation of the left end of vthe machine with a portion thereof broken away to permit of the large scale showing and with one of the cover plates of'the machine removed to better show a portion of its drive gearing.

Fig. 3 is a fragmentary section taken on the line 3 3 of Fig. 2 showing in elevation a portion of the power transmitting gearing of the machine.

Fig, 4 is an enlarged plan view of the machine with a middle portion thereof broken away, with the top part of the machine casing cut away to reveal the horizontally disposed spindle of the vthread-forming apparatus, the gearing for driving the same and the gearing by which the said spindle is operatively connected to drive the carriage feed mechanism which is shown at the right end of the figure where the machine casing is partially broken away.

Fig. 5 is a fragmentary vertical section on the line 5 5 of Fig. 4 showing means for adjusting the carriage-actuating cam.

Fig. 6 is a developmental sectional view taken on the broken line 6 6 of Fig. 2 and showing the major part of the drive gearing at the left end of the machine.

Fig. '7 is an enlarged longitudinal sectional view of the thread-forming apparatus, the section being taken on the line 1 1 of Fig. 9.

Fig. 8 is a horizontal axial section showing the main parts of the thread-forming mechanism shown in Fig. 7.

Fig. 9 is a vertical transverse section on the line l9 9 of Fig, 7.

. the thread cut, Fig. 13 showing the cam device set for cutting a taper thread, while Fig. 14 s hws it set for the cutting of a straight thread,

Fig. l5 is an enlarged reproduction of the middle part of Fig, s to better show the construction of cam mechanism employed for causing gradual retraction of the cutters.

Fig. 16 is a view similar to Fig. 15 but showing the movable parts in the positions occupied after some retraction of the cutters has been effected. Fig. 17 is a longitudinal section on the line I'I-Il of Fig. 16.

Fig. 18 is a transverse section on the line I8-Il of Fig. 16.

Fig. 19 is an enlarged:`- fragmentary plan view` tion taken on the line 23-23 of Fig. 4 and illustrating a portion of the carriage feed mechanism.

Fig. 24 is an enlarged fragmentary transverse section of the machine taken on the line M Zl of Fig. 4.

Fig. 25 is an enlarged fragmentary section taken on the broken line 25-25 of Fig 4.

Fig. 26 is an enlarged rear elevation of a portion of the machine with a considerable part thereof broken away to permit larger scale illustration of fluid pressure control and actuating devices of the machine.

Fig. 27 is an enlarged detail view of one of the valves of the machine and the cam means for actuating it.

l Fig. 28 is a large scale front elevation of portions of the machine, with some parts shown in section, to illustrate theautomatic devices for re-setting the thread-forming chasers following their collapse at the end of the thread-cutting operation, together with manual devices for disconnecting the automatic re-setting means and eiecting manual collapse and re-setting of the cutters.

Fig. 29 is a fragmentary vertical section showing the adjustable connection between the machine carriage and the cam feed device with the said connection broken to permit independent movement of the carriage.

Figs. 30 and 3l are fragmentary detail views of the manual collapse and re-setting devices showing them in positions of operation different from the positions shown in Fig. 28.

Fig. 32 is a diagrammatic view of the fluidpressure-actuated devices of the machine together with their control devices.

Figs. 33 and 34 are fragmentary side elevations showing one of the pilot valves and its actuating ticam in different positions in the cycle of operaons.

Speaking generally. the machine shown in the drawings comprises a main floor-supported frame or casing structure designated as an entirety by the numeral I. 'Ihis frame has at its right end a bolted-on extension la. yAt the left or head end of the machine, as viewed from the front, is disposed thread-cutting apparatus with means for automaticallyeifecting receding and collapsing movements of the chasers. this apparatus being designated as an entirety by the numeral 2. l designates as an entirety a work carriage slidably mounted on ways on the frame I; and 4 designates as an entirety a work-holding gripper orv chuck mechanism for which the carriage structure serves as a supporting frame. A combined fluid and gear operated feed mechanism for advancing and retracting the machine carria'ge is designated as an entirety by the numeral and is best shown in Figs. 4, 23-25. The numeral 6 designates an electric motor for driving the mechanical parts of the machine, the motor being operatively connected with the spindle of the thread-cutting apparatus by av variable speed drive mechanism designated as an entirety by 1, while the numeral 8 designates as an entirety a .variable speed gear drive mechanism between the said spindle and the carriage feed mechanism 5.

The machine further comprises a system of fluid actuated devices for operating and coordinating the movements of various parts and devices of the machine, and this system is designated as an entirety by the numeral 9 (Fig. 26). The machine is provided also with a manually operable mechanism, designated as an entirety by the numeral I0, for collapsing and re-setting the chasers of the thread-cutting apparatus independently of the automatic control of the machine.

The above-noted main portions of the machine will now be described in detail.

THE THREAD-C UTTING APPARATUS As has been stated, the machine shown by way of example in the application drawings is designed to form external screw threads and forv brevity and convenience the thread-forming ap paratus 2 will be referred to as the die, with the understanding that the latter term is not used in a limiting sense.

The die mechanism has a tool body in the form of a hollow spindle which comprises a main part orA body II rotatably mounted at its right and left ends in roller bearings I2 and I3, respectively. A ring nut I4 is provided to afford adjustment for both of the bearings. Keyed on spindle body II are driven and driving gears I5 and I6, respectively, which are secured against axial movement by a spacer sleeve I1 and ring nut I8. In addition to the spindle body Il, the tool body or spindle comprises a head I9 secured to body II by screws 26. 'I'he spindle body II is formed at its front end with iour forward extensions or fingers Ila to which head I9 is rigidly secured by the screws 20. [The spaces between adjacent fingers thus provide four openings through the side wall of the spindle] By providing one of the body and head parts with spaced-apart fingers in this manner the effect is to ,form four openings through the side wall of the spindle.

The head I9 is formed with a plurality of radial slots in each of which is slidably mounted a chaser block 2| which carries at its inner end a chaser 22 secured by wedge block 23. The blocks 2l are slidably secured in their slots by an annular plate or ring 24 which is secured b screws (not shown) to the head I9. l

The chaser blocks and their mounting in the head of the tool body are of well known construction such as is shown in the United States patentl to Benninghofl, No. 2,054,028 (Fig. .13), each block being provided with a pair of coil springs which urge the block radially outward in its guide slot. As the present invention is not concerned with these details they are not fully shown and need not be further described.

The die is provided with a chaser-actuating slide which is designated as an entirety by the numeral 25 and which will generally be referred adjustment of said member 29. The head member 28 is formed with four apertures 28a through which extend the fingers IIa of the spindle body vIl and at points radially inside of these fingers member 28 is rigidly secured by screws 30 to the tubular member 26 of theslide. The fingers IIa by their engagement with apertures 28a key the slide structure 25 against rotation relative to spindle body II. A plurality of set screws 3l mounted in head member 2-9 to engage member 28 serve to hold the member 29 in adjusted position on member 28. A ring 32 having graduations on its peripheral surface is secured on the periphery of the member 28 of the outer slide and suitable reference marking is provided on the adjacent edge of the adjustable member 29 to cooperate with the graduations on member 32 and facilitate the adjustment of member 29 for purposes which will later be explained. A set screw 33 serves to adjustably secure ring 32.

To eifect'the receding movements of the chaser blocks 2| and chasers 22 a cam ring 34 is secured to the member 23 of the outer slide, by a retaining ring and screws 36, so that the ring 34 slidably engages the inner surface of the member 28. To the ring 34 a plurality of cam blocks 31 are secured by screws 38, 39 in position to operatively engage the chaser blocks 2l, the chaser blocks and cam blocks being provided with interlocking tongue and groove cam surfaces in well known manner. which also is disclosed in the above mentioned Patent 2,054,028. With the parts constructed as described, movement of the outer slide and the cam blocks 31 to the left serves to withdraw the chaser blocks outward to effect their receding movement to produce a taper thread.

In addition to the springs, not shown but above referred to as interposed between the head I9 and the chaser blocks 2l to urge the latter radially outward, a plurality of springs 4II are interposed between the head I9 and member 28 of the outer slide, these latter springs tending to urge the outer slide to the left and thus serving to assist the outward movement of chaser blocks 2I during the receding movement thereof.

Within the outer slide 25 is mounted an inner slide structure designated as an entirety by the numeral 4I. This inner slide comprises a main member 42 having flanges 42a and 42b with cylindrical peripheral surfaces that slidably engage the cylindrical interior surface of outer slide member 26. The slide member 42 is formed with an axial bore within which is mounted a workengaging structure 43 which comprises a workengaging pressure pad 43a detachably secured to the main body of structure 43 by screw 43h. The structure 43 is urged to the right in relation to 'the inner slide member 42 by a coil spring 44 but such movement to the vright is limited by nut 45 on the left end of structure 43. Movement of the structure 43 toward the left in relation to member 42 is limited by engagement of shoulder 43o with an opposing shoulder on member 42. The

parts 42 and 43 are keyed together as shown (Fig. 9) to prevent their relative rotation.

`To the left of the inner slide member 42 is another member 46 of the inner slide structure.

This latter member is adjustably secured to member 42 by a screw 41 which rotatably engages hnember 46 and has threaded engagement with an upstanding finger 42c of member 42. The screw 41 can be adjusted in member 42 -by removing the pressure pad 43a to permit the insertion of a slender tool to turn the screw.

The slide member 46 is slidably supported in a cylindrical abutment block 46 which itself fits slidably in the bore of spindle I I but is normally secured against sliding movement thereinby means which will later be described. 49 is a cam bar pivotally mounted at its right end on a pin 56 carried by slide member 46 (Figs. 7 and 17). At its left end cam 46 carries a depending pin 5I which engages the cam slot of a cam 52 mounted in member 46 for a guided sliding movement parallel to the axis of the die. Cam block 52 is adjustably connected by screw 53 to slide memf ber 46. By inserting a screw driver or other suitjable tool in the left end of the die, screw 53 can be turned to adjust cam block 52 to the right or to the left and thereby swing the cam block 49 about pivot pin 50 to vary the inclination of the cam groove of block 49 to the longitudinal axis -of the die. Such adjustment of cam 49 is illustrated in Figs. 13 and 14.

Above the cam 49 is another cam 54 slidably mounted and guided in the abutment 46 for movement at right angles to the die axis. 'I'his cam member 54 has a depending pin which engages a slide block 56 in the cam groove of cam block 46 (Fig. 18), so that the movement of cam 49 with the inner slide eects transverse movement of cam 54. Cam .54 is formed with a tongue 54a which in turn engages a cam groove 51a in the transverse bar 51 which is secured to the left end of the outer slide structure by means of screws 56, 56.

By means of the several cam members last described, one of which (54), it will be recalled, is anchored in the abutment member 46, longitudinal movement of the inner slide structure 4I is transmitted on a reduced scale to the outer slide structure while the movement of the latter is in turn transmitted through a further reduction to the chaser blocks 2|. Provision is thus made for the relatively small receding movement of the chasers which is effected during the threading operation in the cutting of taper threads. By adjusting the cam block 49 on its pivot, as above described, the degree of taper of the thread out can be varied from a maximum corresponding to the adjustment shown in Fig.

13 to the minimum of the adjustment shown in Fig. 14 where the movement transmitted by cam 49 is nil and a straight thread is cut.

A ilanged sleeve 59 is secured by screws 66 in the left end of spindle body I I and the right end of this sleeve serves as a stop limiting movement toward the left of abutment 46. Pressure tending to move said abutment toward the left is constantly exerted upon it by a pair of coil springs 6I, 6I (Fig. l2) which are interposed between the abutment and flange 42a of the inner slide member 42. These springs are supported on rods 62, 62 which are secured to the ilange 42a and slidably engage the abutment 46. At their left ends the rods 62 carry pistons 63 which serve with the cylindrical chambers in which they work, as air dash-pots.

The abutment 46 is normally secured against movement in the spindle body I I by a. pair of diametrically opposite spring mounted latches 64.

` GII-which have bevelled outer ends engaging a latch groove 59a in the sleeve 59. Normally these latches are positively held in locking engagement with sleeve 59 by means of a detent member in the form of sleeve 65 which is formed with a co1- lar 65a that is peripherally flatted at diametrically opposite points to engage the at inner ends of the latches, as shown in Fig. 8. 'I'he sleeve 65 is yieldingly pressed toward the right by coil spring 66 which is interposed between the collar 65a of the sleeve and a circular plate or disc 61 which is removably secured to the left end of abutment 46. The walls of sleeve 65 are formed -`with diametrically opposite slots 65b through which extends a transverse pin 66 the two ends of which are anchored in notches in the annular central boss of the end plate 61 of abutment 46. The purpose of the pin will presently appear.

At its left end the detent sleeve 65 is circumferentially grooved to cooperate with the end oi' a manually operated lever 66 by means of which sleeve 65 can be shifted to the left against the tension of spring 66, in order to release the latches 64 so that the rpressure of the abutment 46 under the urging of springs 6| will cause the disengagement of the latches and permit the abutment to move toward the left in the spindle body II. When such movement, which is rapid, occurs the pistons -63 cushion the movement and prevent undue shock.

A rod or spindle 10 is disposed Within the sleeve '65 for longitudinal movement therein, the rod having direct sliding engagement with the sleeve at its left end and having its enlarged right end ntted with a sleeve 1I which slidably engages the right end of sleeve 65. The transverse pin 66 extends through an elongated slot 10a in the rod 16 so that the latter can move endwise without interference with the pin. The rod 10 is normally urged toward the right by coil spring 12 which at one end engages the large right end of rod 16 and at its other end engages the pin 66. the latter thus serving as an abutment for the spring.

An elongated rod 13 is slidably mounted in the abutment 46 and is disposed parallel to the axis of the die with its left end engaging the right end of rod 1|) and with its other end engaging the nut 45 of the Work engaging slide member 43 so as to transmit movement toward the left of member 43 to rod 16. At its left end the rod or spindle 10 is tted with a pair of ball bearings 14 upon which is rotatably mounted a cylindrical cam 15. This cam is arranged to cooperate with a lever 16 pivotally mounted on a block 11 which is itself slidably mounted on a bracket 16 secured t0 the main frame of the machine. A coil spring 19 interposed between the bracket 16 and the block 11 urges said block toward the right. At its right end the block is tted with an anti-friction roller 11a disposed to engage the end plate 61 of abutment 46. The lever 16 .is tted at its free end with an anti-friction roller to engage the cam 15 and on its upper side the lever 16 is arranged to operatively engage an anti-friction roller carried by operating lever 6| of a compressed air pilot valve 66. The purpose of the air valve will later appear.

VARIABLE SPEED DRIVE GEAR FOR DIE SPINDLE The variable speed spindle drive mechanism designated as an entirety by 1 comprises the driven gear I5 fast on the die spindle body I I. The gear I5 ls driven from the motor 6 by a 9 train of gears which comprises a shaft 32 rotatably mounted on the main frame of the machine and driven by means of belts I3 from the motor. A bevelled pinion. fast on shaft l2 meshes with a bevelled gear 35 on shaft It.

'Spur gears 31 and 'i3 are rotatably mounted on shaft v35 and are provided with clutch teeth to cooperate with al sliding clutch member 35 splined on the shaft. 'Ihe gears l1 and 33 mesh with gears 50 and 9| respectively, fast on countershaft 92 and gear 33 in turn'meshes with the driven gear I5 on the die spindle. As shown in Figs. 2 andA 3, the sliding clutch member 39 can be manually shifted by means of a lever lla mounted on shaft Ilb, which shaft can be manually actuated by hand lever llc which turns shaft 33d on which is mounted lever 83e which in turn is connected by link f with a lever arm 33g on shaft 39h. By shiftingthe hand lever BSc the die spindle can be driven at either of two speeds for a given motor speed.

VARIABLE SPEED DRIVE GEAR FOR CARRIAGE FEED MECHANISM The variable speed drive mechanism designated as an entirety by the numeral 3 and which is operatively interposed between the die spindle and the carriage feed mechanism 5. comprises an elongated main shaft 53 which extends practically from end to end of the machine with bearing supports in the main frame thereof. A second shaft Il (Fig. 6) has a sleeve I5 rotatably mounted thereon with a spur gear I3 keyed to the sleeve and in mesh with driving gear I6 fast on the spindle body II of the die. The sleeve 55 comprises a pinion 91 and an adjacent spur gear 33 is keyed on shaft Il. Spur gear 35 and pinion |35 are keyed on oountershaft |3| and mesh, respectively. with pinion l1 and geai` 53. Shaft 5I is thus driven from spindle body |I with a double speed reduction.

Shaft 5l carries a pinion |32 at its left end which drives a gear |33 fast on shaft III and a gear |35 also fast on shaft I drives gear |55 faston the main shaft 93 through an idler gear unit consisting of a pair of gears |01 and Ill and a splined supporting sleeve |09, the gear |31 being removable from the sleeve to permit substitution of a gear of different diameter. To permit such substitution the idler gear sleeve Il! is mounted on a stub shaft Illa carried by an adjustably mounted arm III. This arm is mounted to swing about the axis of gear |06 and can be locked by clamping screw Illb in different positions to accommodate gears |31 of different diameters. Thus a speed change canbe made by merely changing one gear and adjusting the position of arm Il..

WORK CARRIAGE The work-feeding carriage 3 of the machine comprises a frame structure which is ntted with slide strips |I2 of metal suitable for bearlsassi i l p ing a cam Ill having a straight elongated m 'groove Illa and mounted upon a carrier in the form of a cylinder block I which in turn is slidably mounted in the main frame extension Ia to reciprocate transversely of the machine (Figs. 4, 23, 24, 25). The cam plate III is pivotally attached to the block I|5 by a pivot pin ||5 (Fig. 23) and by clamping screws II1, ||'1 which pass through slots in the plate and permit its angular adjustment.l To effect such adjustment a screw IIS is provided (Fig. 5) which is rotatably mounted on the block |I5 and actuates a nut ||3a that operativelyv engages cam plate IM to move it back and forth as the screw block ill has a depending cylindrical lug llsb ing engagement with ways Ib, Ib formed on the CARRIAGE FEED AND RETRACTION DEVICES The carriage 3 is fed forward toward the die 2 and retracted therefrom by mechanism comwhich fits an aperture in a block I |9c that slidably engages the cam groove Illa. 'Ihe block ||5 is formed with a cylinder |22 having a front cylinder head |23 and a rear head |24.

able block I I5 is a piston |25 having a hollow rod |26 which extends through a stuffing box in the head |24 and at its rear end is secured to a bracket |23 bolted to the frame extension Ia, so that in operation block ||5 reciprocates in relation to the fixed piston. AdJacent the piston the rod |26 has a small hole |21 through which the bore of the rod communicates with the interior of the cylinder |22. The front head |23 of the cylinder is fitted with a restricted air hole |23a.

The cylinder block |5has rigidly attached to it an elongated rack |29 which is arranged to be actuated by pinion |30 keyed on a jaw clutch member I3| which is rotatably mounted on shaft |32 having rotatable bearing support in the frame extension la (Fig. 23). A second clutch member |33 is slidably splined on shaft |32 to engage and drive the clutchmember ISI, a shift lever |34 for the clutch member |33 being mounted on a pivot pin |35 carried by frame extension Ia (Fig. 25). Shaft |32 also carries a drive gear |35 which is driven from gear |31 on shaft 83 through an intermediate gear |38 (Fig. 4).

Itwill be seen that the work carriage of the machine is advanced toward the die by reciprocationl of the cam plate ||4 toward the front of the machine and is withdrawn from the die 4by the reverse movement. The forward feed movement is designed to be effected at relatively low speed by closing the clutch |33 so that the cylinder block ||5 and cam plate IH are driven from the die spindle by means of the rack and gear and other elements of the train of gearing between the cylinder block and the die spindle. The reverse movement of the cam plate ||4, on the other hand, is effected at relatively high speed by disengaging the clutch |33 and admitting pressure fluid through the hollow piston rod |25 into the cylinder |22 so as to effect the return movement of the cylinder block and the cam plate thereon.

MANUAL OPERATION 0F THE CARRIAGE At times it is desirable to move the work carrlage manually and to that end the carriage frame III is fitted with a rack |39, and a pinion Oper-l atively mounted in the cylinder |22 of the slid- Il g I mounted on a transverse shaft Ill rotatably supported in the frame I of the machine meshes with the rack so that the carriage can be moved on its supporting ways by rotation of the shaft.

Such rotation may be effected `manually by applying a hand bar III to a capstan Illa on the shaft (Figs. 1, 20, 22) To permit of the manual actuation of the carriage it isnecessary to breakthe drive connection between the carriage and the cam plate III and to accomplish this the clamping nut |25 of the coupling 'block Il! between the carriage and the cam plate may be backed ofi' to permit lowering of block Il! and the disengagement of its teeth Illa from the notches of plate III.

THE WORK CHUCK R GBIPPER The work-holding gripper or chuck mechanism l is supported and more or less housed by the frame of carriage l. The mechanism as shown in Figs. 19-22, comprises a pair of opposed gripper blocks III, Ill slidably mounted in the carriage frame III. Each of these blocks carries a gripper Jaw I secured to the block by a single screw |45. To secure the accurate positioning of the jaw in relation to the block III and its rigid support thereon so that the jaw will always be held in proper alignment with the axis of the thread-forming die of the machine, the meeting faces of each block I and its mating jaw I are transversely channeled in the manner indicated by Figs. 19 and 21. the channel in the block Ill'extending horizontally while the channel in the jaw extends vertically. This channel formation of the two parts provides the block |43 with flanges Illa which respectively overlap the top and bottom surfaces oi' ljaw I (Fig. 2l) while the channel of jaw I provides flanges IM-a which overlap the vertical sides of block |43 (Fig.19).

The gripper blocks I are actuated by vertically disposed levers I, III which are pivotally mounted intermediate their ends on short shaft sections |41 having threaded holes to engage threaded sections of a supporting shaft I which is mounted for rotation in the carriage frame i I I cassa.

so as to adjustably support the shaft sections 'i |41. The upper ends of levers |45 slidably ilt cylindrical holes in short shaft sections III rof tatably mounted in the gripper blocks |43, joint.'

connection with remarkable freedom of move-f ment between blocks |43 and levers |45 being thus provided. To provide for the easy adjustment of the pivotal supports of the levers I the front end of shaft |45 is rotatably mounted in a sleeve which has a screw threaded engagement with the carriage frame The flanged end of sleeve |50 is notched for engagement with a detent |5| adjustably mounted on frame I. In addition, the rear end of shaft |45 .has fixed upon it a cylindrical sleeve |52 which fis longitudinally grooved to cooperate with a spring detent |53 slidably mounted in frame III.

By loosening. the detent |5| and rotating the lindrical apertures in which the lower ends of levers Ill are operatively engaged, thus forming connections between the blocks and the levers like the connections between the upper ends of the levers and the gripper blocks III. The blocks |51 in turn are driven by a toggle linkage comprising the links |55, |56 which are in turn connected to block |51 slidably mounted to reciprocate in the frame I|| on lines parallel to the axis of the machine (Figs. 19, 20) The block |51 is arranged to be actuated by a lever |55 pivotally mounted on the frame and operatively connected with block |51 by link Illa. The lever |58 is itself driven by a fluid pressure motor |55 comprising a trunnion mounted cylinder Ill enclosing a piston with a rod |5| which is pivotally connected to the free end of lever |55. The motor cylinder may be connected with a source of compressed air or other working uid. It will be seen that when the piston of motor |55 is moved forward toward the threading die the toggle linkage is straightened and the chuck jaws are moved toward each other to grip the work, and on the reverse movement of the motor cylinder the chuck jaws are separated to release the work.

THE WORK-SUPPORTING MEANS To support the work piece and facilitate its en-v gagement by the chuck jaws the carriage is provided with a 'pair of conical rollers |52 which are mounted upon slides |53 that engage ways IIIb on the frame |I|. These slides carry trunnion blocks Ia upon which the rollers are mounted with interposed ball bearings IBI. To provide for adjustment of the rollers |52 toward and from each other a rod |55 is rotatably mounted in a bearing bracket |55 on frame Ill and the rod is formed with screw threads engaging mating threads in the slides |53, one set of the threads being right hand and the other left hand so that rotation of the rod |55 in one direction moves the rollers |62 toward each other while its rotation in the opposite direction moves the rollers away from each other. The bearing bracket |55 is provided with a spring pressed de- 'tent |61 designed to engage depressions in the rod |55 to hold it in different adjusted positions.

AUTOMATIC CHASEB Elli-SETTING MECHANISM Following the rapid collapse of the chasers at the end of the thread-cutting operation caused by the release of the cam abutment block Il, it is -necessary to restore the chasers and the v arious related parts of the mechanism includingl the irmer and outer slide structure and the cam abutment block, to their respective positions occupied at the beginning of the thread-cutting operation. This restoration of the parts referred to as re-setting. 1;1v

in the machine illustrated the re-setting is automatically effected by devices which comprise a re-setting yoke Ill carried by a pivotal support lil on the main frame in vertical alignment with the axis of the die. The upper ends of the yoke arms are fitted with anti-friction rollers |10 designed to engage the ilat annular surface of the outer slide head member 2l adjacent its periphery (Figs. l, 28). The yoke carries a fixed pawl |1| designed to engage the notches of a rack member |11 which is operatively connected to the carriage I. This latter connection is effected through a short shaft section |13 rotatably mounted in the rack, a bolt I1! which slidably engages a hole in the shaft section |13 and a nut |15 operatively engaging the bolt and the caris usually sacas 13 rlage frame to adjustably connect the two parte. The connection of the rack |12 Ito the carriage also comprises a heavy coil spring I1l interposed between the shaft I1! and the head of the bolt |14 and a relatively light coil spring |11 intel'-N posed between the shaft I1! and the carriage frame.4 With thel chasers ofthe die set for a cutting operation and the carriage fully retracted both-of the springs I1l and |11 should 4be under some compression.

The notches of the rack |12 are thesame in number and spacing as the notches of the carriage plate I2I by which the cam follower block III is adjustably connected with the carriage. Thus when an adjustment of the'carriage and the work gripper in relation to the die to any one of six diierent positions is eected by fixing the position of the cam follower block I Il, the pivotal connection of the rack |12 with the bolt |14 permits the lifting of the rack and the .engagement of the yoke pawl with a different rack notch corresponding tothe adjustment of the block III without changing the position of the re-setting yoke in relation to thedie.

In the operation of the machinefor cutting taper threads, as the work piece'is advanced by the carriage in relation to the chasers the outer slide structure 25 of the die moves towardl the left by an amount corresponding to the retraction of the chasers needed for the predetermined taper of the threads being out. To insure that the outer slide 25 shall be free for such movement without interference from the re-setting yoke IBB which is simultaneously moved by the carriage, the position of the pivotal support of the yoke in relation to its connections with the rack i12 and the slide 25 of the die is chosen such that the rack will move the anti-friction rollers |10 of the yoke |68 more rapidly than the outer slide 25 is moved, even for a thread of the maximum taper. O'n the reverse movement of lthe carriage following rapid collapse of the chasers the rack |12 is drawn to the right by the carriage and causes the re-setting yoke Ill to correspondingly move the outer slide 26 and re-set the chasers.

In its re-setting movement the outer slide not only restores the chasers to their initial posi- ,tion ready for the next cutting oper-ation, but Ealso carries with it the inner slide structure and ltne abutment u. This follows from the met that "the train of cam connecting devices which transmit the movement of the inner, work-engaging slide to the outer slide is non-overhauling and, through cam il, is anchored in abutment ll. Hence when the outer slide is moved by the resetting yoke, the outer slide, cams, inner slide andabutment move as a unit "and return to their initial positions. As the abutment moves into its initial position its spring-pressed latches 64 snap into locking engagement with the groove Ita and spring il moves sleeve B5 to the right with its collar 85a in position to keep latches Il in their locking engagement with groove 59a. A suillcient re-setting movement of the outer slide 25 by yoke |68 is insured (without injury Ato the mechanism) by the loaded state in which spring I1! is maintained.

MANUAL CHASER COLLAPSE AND RE-SETTING DEVICES manually. Accordingly the following-described devices are provided to effect the manual colla and re-setting of the die.

Adjacent the stem of the yoke Ill is a cam disc na rotatably supported by s snm ma carried by the machine frame I. This disc is connected bya pair of slotted links |13 with the yoke I through blocks Illv pivotally attached to the yoke and *having a sliding engagement with the slots of the links, thus effecting a lost motionconnection between the links and the yoke. The cam disc I1! is also connected by-a link III with the previously described lever il. the link III having its right end slotted to cooperate with a slide block |82 pivotally attached to the cam disc.

For manual operation of the cam disc I1! a hand lever III is mounted on the front of the machine. But for Interference by shaft il the shaft I18a might be extended to the front of the machine and hand lever llt mounted upon it. To avoid such interference the lever is mounted on a shaft Ina rotatably supported on the'frame I and operatively connected to cam disc I1! by gear l on shaft Illa, gear IIS on shaft I1la and idler gear I on a shaft 'Ilia carried by the frame I.

In Fig. 28 the hand lever Ill is shown in its normal position and it will be seen that by swinging the lever to the left the cam disc I1! is rotated counter-clockwise. This rotation, after some lost motion between disc I1I and link III. serves to move sleeve il to the left, unlatch the abutment block 4t and effect the collapse of the chasers, the corresponding movement of the yoke ISI being permitted by the lost motion connection between it and the links I1.. To permit the stated movement of the cam disc I1I independently of the work carriage the peripheral cam surface of the disc is arranged to engage the extended left end of the rack |12 and swing it upward on its pivotal connection with the bolt |14 enough to disengage it from the pawl I1I of the re-setting yoke. This action is shown in Fig.. 30. When it is desired to re-set the chasers the hand lever III is moved to the right to and beyond its normal position, as shown in Fig. 31. This moves the re-setting yoke III and the outer slide ofthe die to the right to effect the re-setting movements of the various parts of the die in the manner previously described. Also during this movement the cam disc |1l is turned to a position permitting the return of the rack |12 into engagement with the pawl |1I thus restoring the connection between the carriage and the yoke IBB. The hand lever may then be restored to its normal position shown in Fig. 28. In restoring the connection of the pawl I1I with the rack |12 the engagement of the pawl in the correct notch of the rack is insured by the action of spring |11.

FLUID PRESSURE CONTROL DEVICES Referring to the rear elevation shown in Fig. 26

and the diagram shown in Fig. 32, Il1 is a compressed air supply pipe which is connected through a manual cut-olf valve Ill with some suitable source of compressed air. Such a source may be a motor-driven compressor mounted upon the main frame of the machine. Mounted on the rear side of the machine are a cam-actu- 

